The Geochemistry of Natural Waters

PREFACE

1 THE HYDROLOGIC CYCLE

Composition of Rainwater

Hydrology

Groundwater

Groundwater as a Resource and Groundwater Contamination

Nonmeteoric Types of Water

Chemical Terms in Hydrology

Suggested Reading

2 CHEMICAL BACKGROUND

Units and Terminology

Equilibrium Thermodynamics

Equilibrium Constant

Measurements of Disequilibrium

Activity-Concentration Relationships

Activities of Ionic Species

Complex Formation

Apparent Equilibrium Constants

Computer Codes

Review Questions

Suggested Reading

3 THE CARBONATE SYSTEM AND PH CONTROL

Carbonic Acid System

Alkalinity and Titration Curves

Alkalinity Titration

Gran Plots

Calcium Carbonate Solubility

Dolomite

High-Magnesium Calcite

Ground and Surface Waters in Carbonate Terrains

Review Questions

Suggested Reading

4 CLAY MINERALS AND CATION EXCHANGE

Mineralogy and Composition

Brucite [Mg(OH)₂] and Gibbsite [Al(OH)₃]

Kaolinite and Related Minerals

2:1 Clay Minerals

Chlorite

Mixed-Layer Clays

Sepiolite and Palygorskite

Colloid Properties

The Double Layer

Membrane Filtration

lon Exchange

Review Questions

Suggested Reading

5 ADSORPTION

Empirical Equations

Linear Distribution Coefficient

Freundlich Isotherm

Langmuir Isotherm

Surface Complexation

Acid-Base Equilibria

Adsorption of Metal Cations

Adsorption of Anions

The Electric Double Layer

Modeling Adsorption with MINTEQA2

Review Questions

Suggested Reading

6 ORGANIC COMPOUNDS IN NATURAL WATERS

Natural Organic Matter

Structure of Natural Organic Solutes

Functional Groups

Humic Substances

Dissolved Organic Carbon (DOC) in Natural Environments

Organic Pollutants

Solubility and Related Properties

Adsorption

Biodegradation and Bioremediation

Review Questions

Suggested Reading

7 REDOX EQUILIBRIA

The Standard Hydrogen Electrode and Thermodynamic Conventions

Use of Eh as a Variable

Use of pe as a Variable

Definition of pe and Eh by Redox Pairs

Measurement of Eh

Redox Calculations Using WATEQ4F

pe-pH and Eh-pH Diagrams

System Fe-O-H₂O

System Fe-O-H₂O-CO₂

System Fe-O-H₂O-S

Eh-pH Diagrams

Partial Pressure or Fugacity-Fugacity Diagrams

Review Questions

Suggested Reading

8 REDOX CONDITIONS IN NATURAL WATERS

Photosynthesis

Respiration and Decay

Redox Buffering

Lakes

The Ocean

Groundwater

Summary

Review Questions

Suggested Reading

9 HEAVY METALS AND METALLOIDS

Sources of Heavy Metals

Speciation

Organic Matter and Complex Formation

Equilibrium Solubility Control

Solubility in Redox Reactions

pe-pH and Eh-pH Diagrams

Roll-Front Uranium Deposits

Adsorption and Coprecipitation Controls

Adsorption by Hydrous Iron and Manganese Oxides

Adsorption by Silicates and Carbonates

Adsorption by Solid Organic Matter

Uptake by Living Organisms

Behavior of Specific Elements

Copper, Zinc, Cadmium, and Lead

Arsenic and Selenium

Chromium

Mercury

Summary

Review Questions

Suggested Reading

10 STABILITY RELATIONSHIPS AND SILICATE EQUILIBRIA

Solubility Equilibria (Congruent Solution)

Solubility of Magnesium Silicates

Solubility of Gibbsite

Solubility of Aluminosilicates

Incongruent Solution and Stability Diagrams

Uncertainty in Mineral Stability Diagrams

Review Questions

Suggested Reading

11 KINETICS

Nucleation

Dissolution and Growth

Surface Reaction Mechanisms

Diffusion Control

Dissolution of Calcite in Seawater

Growth of Calcite and Aragonite in Seawater

Dissolution of Silicates

Effect of Solution Composition on Dissolution Rates

Relative Dissolution Rates of Different Minerals

Comparisons Between Laboratory and Field Dissolution Rates

Review Questions

Suggested Reading

12 WEATHERING AND WATER CHEMISTRY

Soil Formation

The Mass-Balance Approach to Catchment Processes and Mineral Weathering Reactions

Catchment Processes

Mineral Weathering Reactions

Mass-Balance Calculations in Groundwater Systems

The Thermodynamic Approach to Mineral Weathering Reactions

The Statistical Approach

Case Studies

Mackenzie River System, Canada

Amazon and Orinoco River Systems

Absaroka Mountains, Wyoming

Mattole River, California

Cascade Mountains, Washington; Loch Vale, Colorado

Adirondack Mountains, New York

Waters from Ultramafic Rocks

Rhine River

Summary

Thermodynamic Controls on Clay Mineral Formation

Environmental Factors and Water Chemistry

Review Questions

Suggested Reading

13 ACID WATER

Acidity and Alkalinity

Solubility of Aluminum Hydroxide

Acid Deposition

Cation Exchange

Anion Mobility and Anion Exchange

Processes Affecting Sulfate Mobility

Biological Processes

Chemical Weathering

Integrated Models

Environmental Effects

Acid Mine Drainage

Prediction of Acid Generation

Prevention of Acid Generation

Review Questions

Suggested Reading

14 ISOTOPES

Stable Isotopes

Fractionation Processes

¹⁸O/¹⁶O and D/H

¹³C/¹²C

³⁴S/³²S

¹⁵N/¹⁴N

Radioactive Isotopes

Tritium

¹⁴C

Chlorine-36

Radon 222

Radiogenic Isotopes: Strontium-87

Review Questions

Suggested Reading

15 EVAPORATION AND SALINE WATERS

Evaporation of Sierra Nevada Spring Water

Chemical Divides and the Hardie-Eugster Model

Modifications of the Hardie-Eugster Model

Magnesium Carbonate Formation

Sulfate Reduction and Sulfide Oxidation

Ion Exchange and Adsorption

Cyclic Wetting and Drying

Examples

Lake Magadi Basin, Kenya

Teels Marsh, Nevada

Evaporation of Seawater

Persian Gulf Sabkhas

Saline Formation Waters

Summary

Review Questions

Suggested Reading

16 TRANSPORT AND REACTION MODELING

The Advection-Diffusion Equation

Advection

Diffusion and Dispersion

Chemical Reaction and Retardation

Reaction Path Modeling

Application to Contaminant Transport in Groundwater

Chemical Evolution of Groundwater

Review Questions

Suggested Reading

REFERENCES

GLOSSARY OF GEOLOGICAL TERMS

APPENDIX I PIPER AND STIFF DIAGRAMS

APPENDIX II STANDARD-STATE THERMODYNAMIC DATA FOR SOME COMMON SPECIES

APPENDIX III EQUILIBRIUM CONSTANTS AT 25°C AND ENTHALPIES OF REACTION FOR SELECTED REACTIONS

ANSWERS TO PROBLEMS

AUTHOR INDEX

SUBJECT INDEX